.cal{
    background-color: gainsboro;
    width:210px;
}
.content{
    width:210px;
    height:280px;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
}
.content div{
    border-radius: 50%;
    box-sizing: border-box;
    width:50px;
    height:50px;
    border:1px solid gray;
    background-color: ghostwhite;
    /* 字体居中 */
    display: flex;
    justify-content: center;
    align-items: center;
}